1. Field of the Invention
The present disclosure relates to an optical read/write apparatus that reads, writes or erases information from/on an optical storage medium such as an optical tape, an optical disc or an optical card. More particularly, the present disclosure relates to an apparatus that carries out read/write operations in parallel with each other using multiple optical pickups.
2. Description of the Related Art
Recently, the size of digital data that can be stored on a storage medium has been rising steeply year by year as the resolutions of video data and still picture data have been tremendously increased and as increasing numbers of paper media have been converted into electronic ones. Meanwhile, so-called “crowd computing” technologies that allow people to use various kinds of applications and services via servers and storage systems on some network have become more and more popular nowadays. According to such crowd computing technologies, as a huge number of users save various kinds of data on that storage system on the network, the amount of data accumulated there should keep on skyrocketing from now on.
In the meantime, as regulations have been established one after another with regard to the duty of preserving such a huge amount of data saved, it should also be increasingly important to devise a method for saving that enormous amount of data as securely and as reliably as possible.
Japanese Laid-Open Patent Publication No. 2004-54983 (which will be referred to herein as “Patent Document No. 1” for convenience sake) discloses a configuration for increasing the data transfer rate at which a read/write operation is performed optically by an apparatus on an optical storage medium. The apparatus disclosed in Patent Document No. 1 arranges multiple optical pickups with respect to a given optical storage medium and performs read/write operations in parallel with each other using those optical pickups simultaneously. In order to increase the data transfer rate, the number of those optical pickups arranged needs to be large enough to cover every track of the optical storage medium.
Hereinafter, an example of an apparatus as disclosed in Japanese Laid-Open Patent Publication No. 2004-54983 will be described with reference to FIG. 9. In this example, the apparatus is supposed to be able to perform read/write operations simultaneously using three optical pickups 2. The relative positions of the optical pickups 2 with respect to the optical tape 1 are fixed. Each of those optical pickups 2 includes an objective lens 3 and a lens actuator that drives the objective lens 3. The lens actuator can shift the objective lens 3 in a track crossing direction (i.e., in a tracking direction). Although the optical pickups 2 are fixed, their objective lens 3 does shift. In this manner, each of those optical pickups 2 can cover a plurality of tracks included in an area with a width Wr. Each optical pickup 2 can follow, and can read and write data from/on, any track falling within its own range.
In the following description, the “track crossing direction” will be sometimes referred to herein as a “tracking direction” and the magnitude of shift of the objective lens 3 in the tracking direction for the purpose of performing a tracking operation will be referred to herein as the “magnitude of lens shift”.
Supposing the number of optical pickups 2 arranged is twelve, the trackable range in which each of those optical pickups 2 can perform a read/write operation by shifting its own objective lens is Wr, and the overall track range of the optical tape 1 is W, the read/write operations can be performed on every track on the optical tape 1 ifW=12×Wr is satisfied.
By performing read/write operations simultaneously using those twelve optical pickups 2, a high data transfer rate can be obtained.
However, each optical pickup includes a light source and lens actuator that dissipates power and generates heat. That is why if the number of optical pickups provided for an optical read/write apparatus increases, then the power dissipation and the quantity of the heat generated will both increase.
According to an embodiment of the present disclosure, when read/write operations are performed simultaneously using multiple optical pickups, the power dissipated and the heat generated can be reduced.